Flotation of minerals



Dec. 26,1922. 1,449,129

FLov'f'A'rOr 'oncma Fuso Aus. 30, i919. 2 SHEETS-SHEET l w3 Wim! ggd/Mt @nnen/im (Muay Patented Der. 26, i922 WALTER 0. BORCHJERT, F AUSTINVELLE ZINC COMPANY, OF NEW YRK, N.

, niacin-ie, assitance To Tea new JERSEY YZ, t CORPORATEON OIF NEW' JERSEY- Applieation iled August 30, 1919. Serial No. 320,861.

T 0 all whom t muy concern.'

Be it known that l, WALTER O. BonoHnnDT, a citizen' of the United States, residing at Austinville, in the county of VVythe, State of Virginia, have invented certain new and useful lmprovements in Flotation of Minerals; and l do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art 'to which it appertans, to make and use the same. rlhis invention relates to the flotation of ores and other substances amenable to flotation. More particularly, it relates to iinprovenientel titi' the so-called )neumatic process of flotation, in which the air or other gaseous fluid is introduced into the ore pulp through the porous bottom of the flotation cell, or its equivalent, and, as the pulp contains a suitable frothing and flotation agent or agents, the lloatable constituents are raised bythe air bubbles and caused to overflow as a froth, into suitable launders, whilst the non-fioatable constituents, together with the bulk of the water, are eventually discharged from the end of the cell as tailings. ln flotation apparatus of this general type, the ore pulp is introduced continuously at one end of the flotation cell, and the tailings pass out at the opposite end thereof, the Jfroth being removed by overflow into the launders. j

It has been the commonpractice to provide such flotation cells with a rather steeply inclined bottom, 'throughuwhich the air is intreduced, the inclination of the bottom assisting* in the preventionl of settling of the solids of'thepu'lp and the consequent obstruction or blanketing of, the porous material forming the bottom. Such steeply inclined porous bottoms in lotationcellsare, however, objectionable.` These objections are in part as follows;.Steepinclination of' the porous bottom results in' av reat variation of the depth of Pulp in di erent .per-

tions of tbecell, and, since the rate'of dow' of the air thru the porous bottom 'isf'.in4

part a function of the head of pulp above the porousl bottom,fit follows that inonder to maintain an approximately uniform emission of air7 the pressure of compressed".

air at the shallow end of the cell must be made less than that at the deep end ot the cell. ln order to make such regulation possible, the porous bottom is ordinaril; di-

vided by partitions into a plurality o' airboxes, the length of each of which, measured o n the length of the cell, is comparatively small. Each oi` these individual air-boxes or compartments must be separately pi ed -rom the main air supply header, lan be the extent to which this occurs, as it will y be plain that the more difficult a particle of valuable mineral is to float, the more important it is to subject it repeatedly to conditions under which its flotation maybecome possible, so as to insure, to the greatest possible extent, its ultimate removal'by the froth; -and obviously, if a coarse particle of` valuable mineral which tends to hug the bottom, is carried thru the cell, not only at the' rate corresponding to the average rate of flow of the Wholepulp, but at'an increased lvelocity, `due to the'component'of gravity Vfall, which the steeply inclined bottom tends to impart, it vwill be subjected' to the action of the cell for a shorter period than that of the average particles. of the pulp, and i as it approaches the deep or discharge end of the cell, the probability of its being car-A ried into the froth becomes'increasingly f more remote` A further disadvantage of steeply 'inclined flotation cell bottoms results'from the reduction in internal cubic contents for a given floor space and mill lieiglit occupied by the cell. This loss in volume ,with the steeply inclined betteln may range from 15 to 30% of the volume, which could have been secured within the saine horizontal and vertical limits bye. cell having a horizontal or approxiniattl;Y horizontalV bottom.y For example, if the volume of a cell, included Within certain horizontal and vertical diinensions,is a thousand gallons.J and it is fed with pulp at the rate of 100 p. ni. the average duration ot exposure ot'a particle in the pulp should be l0 ininutes, and it is one of the primary objects in 'the design of such cells to insure each particle of thesaine treatment, both as to time and intensity, as all other particles. lf, bythe steep ,inclination of the bottoni 20% of the possible volume has been lost, the result'will be aloss of 207,7 ofthe possible duration of treatment, irrespective of the considerations previously mentioned, whereby ,the steep inclination of the bottom reduces the average 'duration of treatment of the coarser )articles Various mechanical devices have at different times been proposed to prevent the settling of portions' of the pulp, and the consequent olanketing' of the porous airemitting; sui-face, but, such mechanical de' vices have been of very limited utility, since they have, in general, operated to hasten, rather than retard, the rate of progress thru the cell of the coarser or less amenable particles of valuable mineral. "lhe need for such mechanical devices has resulted chiefly from theiiriegnilar and iin/ever emission of air thru the porous bottom., ince-it is obvious that under conditions where a substantially uniform emission of airis provided, the settling of partiles small enough to he within the range of iintation should be impossible. f

lo pneumaticflotation cells 'of all types,

it has been customary to provide ballies eX-.

tending from the froth overflow line, or

slightly above it, downinto the body of the pulp.` Such hailies are generally arranged transversely to the length of the cell, and are ordinarily in an approximately vertical plane, their purpose being to prevent the longitudinal movement of the froth, causing it to overflow where formed, -makinff possible, when desired, the collection or'. rich froth from the feed end of the cell, and leaner froth from the lower end of the cell, while at the' same time localizing the effect of excessive fr ee oil, or other froth breaking or. froth killing. agencies.,

So also, it has been pro-posed to provide y flotation cells of this saine general character with a horizontal or bottom, and toprovide downwardly extend` of 'the porous ell'ect is thereby .ingr through the bottom so that a produced' by all but slightly sloping",`v v bn the line 3-3 of Fig. ing ballleswvith their lower edgesseparated a short distance from, the upper''surfacesy bodiesare maintained substantially separate,

except for the ore pulp vwhich is continuously liowing into and out therefrom. 5

, ln the improved apparatus of the present invention, the flotation cell, which is of the pneumatic type, is provided with a plurality of partitions extending' upwardly from the cell bottoni and dividing' the lower portion of the cell into a series of separate compart-i ments, each provided with a porous bottoni, or its equivalent, through which the air or other gaseous iiuid is introduced. The height of the partitions separatingthe ditferent compartments is such that the ore pulp, in flowing from one compartmentto the next, is caused to pass upwardly to wards the under surface of the froth as it passes over each partition. The actionA of the partitions is, therefoige, to provide a' series of successive bodies of pulp, from one to another pf w ich the dre such a manner that each body of pulp is independently subjected to the iiotationoperation, and values continuously removed therefrom, while the ore pulp lowintgl .from one compartment to the next is caused to pass upwardly towards theunder surface of the froth.

The action of the partitions extending uppulp flows in v wardly from the bottomof the flotation cel'lby depending' ball'les to, or a few inches practiced.

, 'In the acconrpanyi ng drawings,4

Fig. l is a plan view of an apparatus illustrative of the invention.;

Fig. 2 is' a vertical sectionalview olf th .flotation cell or apparatusof Fig.

Fig. 3 is a transverse vertical section'taken Fig. 4 is an enlarged view of one oft-he air compartments. Fig. is avertical longitudinal section of .a modified construction' illustrative of flic invention 5 l Fig.' 6 is a plan view of the apparatus ot Fi lgiligxi? is a sectional vie,7 on the line r1-*7 of Fig. 5; and

Fig. 8 is an enlarged view of one form ol porous bottom.

Referring first to the apparatus illustrated in Figs. l to 4, it will be seen that the cell is constructed with the usual side walls l. and launder 2, and with the inlet 3 at one end ol the cell for the supply of the 4ore pulp and the outlet l at the other end for the removal of the tailings. Extending up\\'ardly from the bottom of the cell are the partitions :3, of substantially the same height, so thatthe tops of the partitions lie in a plane substantially parallel to the plane of the bottom ot the cell. The bottom of the cell is slightly inclined from the inlet 3 to the outlet fr so as to provide the desired flow ot' the pulp vthrough the cell b'y the action ot gravity.

intermediate the partitions 5 are depending bailles (l, which are adjustable in guides 7, and which extend down to. or a few inches below, the normal pulp line ot the cell. These batlies can be raised or lowered to dil"- ferent heights, but they will be arranged at such a height from the bottom ol' the ccll lthat no appreciable' scouring effect upon the bottom of the cell is occasioned thereby, and the principal, object 1n positioning them between guides is to make them readily re .provided with regulating valves (not shown) movable when it is desired to inspect or re place an air chamber or compartment.

It will be noted that the partitions divide the apparatus into a series of compartments, in each of which is provided means for the introduction of a compressed gaseous fluid, such as compressed air, by means ot which the flotation is to be effected. ln the form ot the invention illustrated,` the air compart ments 8 areforined of a metal box having a perforated metal cover 9 thereon, above wh ich are arranged the layer or layers of canvas or other matorial'- 10. '.lhe compressed air or other gaseous fluid is supplied by the sup ply pipes l1, which lhave transverse openings l2 communicating with the compartments 8. The various parts of the compartment are secured together in any suitable manner.

A common header 13 is provided for sup'- plying the compressed air to the supply pipes l1 of the various compartments of the cell, and these various supply pipes can be for independently regulating the supply ot compressed air to the separate compartments. inasmuch as the bottom of the cell is substantially horizontal, the difference in the head of pulp will vary but little from one end of the cell to the other, and the variation in the air pressure required will be correspondingly moderate. v

y The llotationcell is provided with the usual baille 14, to prevent interference by thc indowing pulp, and with the outlet compartment l containing the adjustable outlet partition 1G. The tailings flowing from the apparatus are pumped by the pump lbto another flotation machine 't'or retreatment, or to other place of treatment, or to waste. .This pump may be drivenl by any suitable means, as by a pulley 2() and the belt lf). similar pump 2l is arranged to receive the froth from the launders 2 through the pipe 22, and pump it. to its piace of further treatment. l

ln the operation of the apparatus, the ore pulp or like material to be subjected to the flotation operation is introduced at the inlet end ot the apparatus and is caused to flow progressively from one to another ot the separate compartments formed by the partitions ln each ot these compartments it is subjected to a flotation operation, while the partitions force the heavier portions of the ore pulp upwardly toward the under surt'ace of the froth at each passage oi' the pulp ther-cover. i`he flotation of such particles isthereby promoted. lVhereas, in the ordinary type ot' pneumatic flotation cell, whether ot' the steeply inclined bottom or of the Substantially horizontal bottom kind, and whether or not equipped with battles depending Jfrom the top and extending either just, below the body oi froth, or almost to the aireinitting surface, the tendency is toward llas-telling thru the cell the coarser particles of valuable mineral, or those less amenable to flotation, the arrangement of the' cell ot the present invention is Such that the heavier particles, or those leerl amenable to flotation, are held in the cell for at least as long a period as any others. In the-first compart ment, included betvl'een the feed end of the cell il, and the lirst partition 5, there is formed whatamonnts to a trap, in which are caught and retained particles too coarse to be carriedh thru the cell by the normal rate'ot flow, and the suspension resulting from the passage of the myriad ot' air bubbles thru the pulp; Such unduly coarse par ticles may be intermittently or continuously discharged from this first compartment by means oi a bottom spigot orside-draw 30 as willlbe readily understood by those skilled in the art, and as is commonly practiced with ore classiliers. The body of froth held above the first compartment between the feedv end of the cell, and the iirst depending battle lents, and the-n passing underthe dependballles 6 before overflow into the neat compartments. These dependingl hotties form separate bodies ol truth which ovcrflow from the particular compartments where they ire produce The function of the depending battles is secondary, and they` t 21" appended thereto. lhe cell has a substantially `horizontal bottoni and is provided with4 partitions 5"'attending` upwardly `trom the bottom to progressively decreasing heights, so that the ore pulp, in its passage through the cell, will be caused to overflow these par titions progressively from the inlet to the outlet end ot' the cell, and so that. the ore pulp will be. caused to flow by gravity from.

one compartment to the next and subjected to successive and progressive dotation operH ations in these separat-e compartments. rlie froth produced will, however, all be collected in the common launder 2u.

ln the apparatus of Figs. 5 to T, the compressed air supply pipe 13a is arranged 'oe-- louY the cell and has branches lla supplying the compressed: air to the air compartment 8 at the bottom of the separate flotation compartments.

The porous vhottom ilhistrated in 'this modification oij the invention is. made` up of a layer of metallic spherules or shot 25, supported in any suitable manner, as by means ot' the layer of canvas 24 which, in turn, is supported bythe screen Q3. This form of orous bottom is more fully described in letters Patent of' the `United aies, No. 1,326,17, patented December 30, 191.9. Such l a. layer of metallic spherules has the ad* vantage of giving a substantially uniform discharge. of air' bubbles of uniform size.

The depth of the layer ot' metallic spherules and the fineness ofthe spherules can'be valried depending upon the desired iineness of 'the air bubbles to be produced. Spherules of a diameter of 0.,()8 inches to 0.03 inches or from No., 9 to fine dust American standard may be employed, and of a depth of fromv 1 about one/halt inch to one inch or even. tivo inches or more. The depth or the layer ot spherules' or shot will naturally vary with the nature of the supporting diaphragm and with the result desired1- With even Veryy fine spherules the separate partitions 5 prevent the spherules from being. carried from one compartment to another,` eventhough vthe spherulcs may besoitiewlfiatdi and agitated by the upward passage or discharge of air therethrough.

lt will accordingl vvloe noted that the pres-A ent invention provi esan-improved flotation cell or apparatus of the pneumatic type, 1n wl'iich thp cell is divided into a `series'or" compartments, from one to another of which the ore pulp flows, with the result that the ore pulp is subjected to the :dotation operation in a series of successive and more or less .independent bodies, While the Ore pulp, in its overflow from one compartment to the next, is caused tov pass upwardly so that the heavier 'portions are directed toward the un-A der surface of the froth at each passage over the partitions and the flotation operatio thereby promoted. i

The treatment of the ore pulp in the im-.

proved `apparra-tus accordingly involves, as a method ot' treatment or procedure, thesupplying of the ore pulp in a continuous manner to the flotation apparatus, and the subi ecting of thelpulp therein to a series of progressive and successive flotation operations,

during each of `which the ore pulp is sub jet-.ted to the pneumatic {lot-ation, and be roo vention, much as they have heretofore been commonly used in the 'pneumatic flotation process. The flotation agent, such as an oil or mixture of oils, can thus be preliminarily incorporated with the. `ore pulp beforeit is supplied to the flotation cell, so. that, during the passage of the "ore pulp through thecell, 'the flotation agent will be. present and willpronuote the flotation operation, in a manner which will be readily understood.

1. The method of concentrating minerals and otherloatable substances bythe pneumatic process of flotation, which comprises continuously supplying ore pulp to a'ilotation apparatus and removingI the tailings therefrom, subjecting the ore. pulp in` its flow through said apparatus to a series ot separate and successive flotation operations in the course oli' eachol which operations the ore pulp is caused to llow downWardly. repeatedly directing the ore pulp (in its flow through said apparatus) upwardly toward the under surface of the froth during the passage ot' thelore pulp from one flotation operation to a successive flotation operation and' While the ore pulp is continuously subjecied the flotation operation andso that, the regions of the' vpulp upflow as welles the Maniac regions o''iulpdowntlow are longitudinally intended and. overlic'regios of delivf'eryv ofv wardly in each compartment, means for in troducing finely divided air or other gaseous luid into thebottom of each of said com partnients, and means for supplying 'ore pulp to one end of the apparatus and for removing the tailings from the other end of the apparatus, whereby the ore pulp in its flow through the apparatus from one compartment to the next is caused to overflow the partitions and is thereby directed upwardly toward the under surface oitthe froth while being continuously subjected to the flotation operation, theaters-,mentioned gas introducing means being so arranged that the regions of pulp uploiv as well as the regions of pulp downlow are longgfitudinail)7 extended and overlie regions of delivery of fine gas bubbles.

3. A flotation apparatus of the pneumatic type provided with a series of partitions extending upwardly -from the bottom of the apparatus and dividing` the same into a series of separate compartments, means for introducing finely divided air or other gaseous fluid into the bottom of each of said compartments, downwardly extendingf bullies operatively arranged in said apparatus and so spaced from said partitions and iron'l the bottom of the apparatus as to provide unrestricted passages for the flow of ore pulp between the partitions and battles and beneath the baffles, and means for supplying orc pulp to one end of the apparatus and for removing the tailings from the other end of th'e apparatus`r whereby the ore pulp in its passage through the apparatus from vone compartment to the next is caused to overflow the partitions and flow under the dependlngr baffles while being continuously subjected to the flotation operation, the aforementioned gas introducing means being so arranged that the regions of pulp uptlow as well as the regions of pulp downlow are longitudinally extended 'und overlie regions orl delivery of .tine bubbles. '4. A flotation apparatus of the pneumatic type provided with a series of partitions extending upwardly from the bottom of the apparatus to progressively decreasingl distances and dividing the apparatus Iinto a series of separate compartments, means for introducing finely divided air or other gaseous fluid into the bottom of each of said compartmentaand means for supplying ore pulp to one'end of the apparatus and for removing the tailings from the other end of the apparatus whereby the ore pulp in its passage through the apparatus from one corn-V partment to the next is caused to 'overflow the partitions and is thereby directed upwardly toward the undersurface of the froth.

5. A flotation apparatus of the pneumatic type provided with a series of partitions eX- tending upwardly from the bottom of the apparatus and dividing the apparatus into a series of @parate compartmentsI` depending baiiies operatively arranged in said apparatus Aand so spaced from said partitions and from the bottom of the apparatus to provide unrestricted passages for the flow of ore pulp between the partit-ions and baliiles and beneath the bullies. means for supplying ore pulp to one end of the apparatus and for removingI the tailings from the other end of ,the apparatus. whereby the ore pulp in its passage through the apparatus from one compartmentto the next is caused to overflow the partitions and flow under the depending battles, and means for introducing finely divided air or other gaseous fluid into the bottom oi each of said compartments so that the regions or" pulp uplow well as the regions ot' pulp downlow are longitudinally extended and overlie regions of delivery of fine gas bubbles.

6. A flotation apparatus of the pneumatic type provided with a series of partitions extending upwardly from the bottom of the apparatus to progressively decreasingr distances and dividing the apparatus into a series of separate compartiments` means for supplying ore pulp to one end oi the apparatus and i'or removing the tailings from theI other end of the apparatus, whcrebv the ore pulp in its passage through the :qiparatus from one compartment to the next is caused to overflow the partitions and means for introducing iinely divided air or other gaseous fluid into the bottom oi' each of said compartments so that the regions ot' pulp upfiow as well as the regions oi pulp downlow are longitudinally extended and overlie regions of delivery of line gas bubbles.

7. flotation apparatus of the pneumatic type provided with a series of partitions extending upwardly from the bottom of the apparatus to progressively decreasing' distances and dividing the apparatus into a series of separate compartments, depending ballles operatively arranged in said apparatus and so spaced from said partitions and from the bottom of the apparatus as to provide unrestricted' 'passages' for the flow of Aore pulp between the partitions and baffles Lemme its passage hxougzh the ppa'atus from one hm', the regions of pup upow as Weil vas compartment to the next i5 caused to over the; regions of pup downow are on'gitudflow the partons and flow undef the de-I nally extended and overle legions of dezpending' bmies, and means for introducing livery of ne gas bubbles. 1 5 finely divided air or other 'gaseous uid into in testimony whereof affix mysignatme. 'the bottom of each of said compartments so LTER O.' BORCHERDT, 

